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With a Third Wave on the Horizon, a Closer Look at Kolkata’s Vaccination Coverage

With a Third Wave on the Horizon, a Closer Look at Kolkata’s Vaccination Coverage

A man applies finishing touches to graffiti showing a vaccine, in Kolkata, January 2, 2021. Photo: Reuters/Rupak De Chowdhuri

Kolkata: Everyone – including mask-at-chin daredevils – seems to be endlessly worried about the coming of the ‘third wave’. But there is reason to be optimistic even after having witnessed the carnage of India’s second wave – i.e. the country’s second major outbreak of COVID-19 – that the next time may not be as bad.

West Bengal has a rich tradition of public vaccination. The latest National Family Health Survey (#5) results show that the state has been vaccinating people quite well over the years. For example, according to the survey, 87.8% of all children aged 12-23 months have been fully vaccinated. There has also been praise for the efficient way COVID-19 vaccines have been used by the state’s healthcare staff.

But as things stand, India’s major limitation over the last year or so has been the absence of granular data. Of course, some states have done better to present pandemic-related statistics, but most states –  including West Bengal  –  could have presented more medically relevant data in the daily bulletin. So before we celebrate, it would be useful to look into medically meaningful data about the progress of vaccination in different parts of the state.

As of July 20, West Bengal had administered approximately 26.7 million COVID-19 vaccine doses across its 23 districts. The state’s adult population is around 72.6 million, so 18.3% of the total 145.3 million doses necessary for 100% coverage have been administered.

Of this, 7.8 million people (10.7% of the population) have received both doses. Another 15.3% of people have received one dose. Overall, around 26% of the people have received at least one dose. Among India’s five big-population states, West Bengal’s coverage is comparable to that of Maharashtra and Madhya Pradesh.

But if we’re to understand how the novel coronavirus spreads between individuals in a dense city like Kolkata, just city numbers won’t suffice. Administrative boundaries like municipality wards and districts don’t exist in the virosphere of SARS-CoV-2. The only thing that matters to viral particles is which humans are proximate and for how long.

Second, every day several lakh people travel in and out of Kolkata as part of their livelihoods, mostly to/from the neighbouring districts of  Howrah, North 24 Parganas and South 24 Parganas.

Many of these people travel in crowded buses, trains and taxis, and interact with many others every day. The partial lockdown and travelling limitations (e.g. local trains remain suspended and the large student population is not traveling) have reduced the commuting population compared to pre-pandemic times, but it is still considerable. Any host-virus interplay analysis will be incomplete without accounting for this inter-district mobility.

An additional point is that it’s not easy to estimate Kolkata’s and the three neighbouring districts’ respective populations. The last national census concluded a decade ago. But fortunately, the Election Commission website has the numbers of electors in each constituency. An intensely fought state election ended less than three months ago, so the website’s numbers are as good as new. The electors’ list is also useful because the population of electors is equal to the population of those eligible for COVID-19 vaccines – i.e. people older than 18 years.

So we can proceed with a brief analysis of vaccination coverage based on this data.

The following table presents the populations of the four districts in question and their vaccination statuses.

Source: Author provided

The number of doses is the cumulative figure because of the considerable on-ground overlap between the people of these districts. In addition, areas like Salt Lake, Baranagar, Kasba and Tollygunge are administratively within the two 24 Parganas districts but conventionally considered to be within Kolkata.

The results of the analysis are encouraging.

As of July 20, 13% of the people in these districts had received both doses; another 22.4% had received the first dose. Effectively, a third of the collective population of Kolkata, Howrah and the two 24 Parganas have received at least one dose.

Kolkata and North 24 Parganas deserve a closer look as these two districts have been the joint epicentre of West Bengal’s COVID-19 epidemic. Here, 17.9% have received both doses and 34.6% have received one dose – so at least half of their adult citizens are at least partially protected (notwithstanding the impact of the delta variant).

According to reports by Bartaman and Pratidin, two popular local newspapers, the fraction of people vaccinated is currently 60-70%. So while there is a considerable way to go to 100% coverage, the numbers are encouraging.

There is considerable socioeconomic and gender-based non-uniformity in vaccine distribution, particularly in the districts, according to data on the CoWIN platform. Kolkata also has a higher fraction of people vaccinated than the state’s average – and also the average of its three neighbouring districts. Policymakers should be mindful of this gap because the real number of Indians killed by COVID-19 is 6-10x the official tally, and the best way to protect people is rapid and efficient vaccination. With large tracts of the rural population unvaccinated, there is not a moment to lose before the third wave gets here.

The vaccination coverage read together with recent research based on real-world data, that even one dose of some vaccines provides a meaningful amount of protection against infections of the novel coronavirus, offers a lot of hope. For example, a single dose of the Oxford-AstraZeneca vaccine – ‘Covishield’ in India – is reportedly 61-68% effective against SARS-CoV-2 infections, more so against severe disease.

So it’s not unreasonable to hope that the progress of vaccination in Kolkata and its neighbouring districts will lead to relatively fewer cases of hospitalisation and deaths than in the previous months – but at the same time there is a long way to go. And vaccines alone won’t be enough: the people must keep masking, maintaining physical distances and ventilating their rooms and buildings.

If they don’t, even the immune systems of vaccinated individuals will be under greater stress.

Anirban Mitra teaches molecular biology and biotechnology in Kolkata.

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